In order to meet the increasing wireless data traffic demand since the commercialization of 4G communication systems, the development focus has been on the 5th Generation (5G) or pre-5G communication system. For this reason, the 5G or pre-5G communication system is called beyond 4G network communication system or post Long Term Evolution (LTE) system. In order to accomplish high data rates, implementation of the 5G communication system on the millimeter Wave (mmWave) band (e.g., 60 GHz band) is being considered. In order to mitigate propagation loss and increase propagation distance, the 5G communication system is likely to accommodate various techniques such as beamforming, massive MIMO, Full Dimensional MIMO (FD-MIMO), array antenna, analog beamforming, and large scale antenna. Also, for throughput enhancement of the 5G communication system, research is being conducted on various techniques such as small cell, advanced small cell, cloud radio access network (cloud RAN), ultra-dense network, Device to Device Communication (D2D), wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), and interference cancellation. Furthermore, the ongoing research includes the use of Hybrid FSK and QAM modulation and Sliding Window Superposition Coding (SWSC) as an Advanced Coding Modulation (ACM) scheme, Filter Bank Multi Carrier (FBMC), Non-Orthogonal Multiple Access (NOMA), and Sparse Code Multiple Access (SCMA).
Meanwhile, the Internet is evolving from a human-centric communication network in which information is generated and consumed by humans to an Internet of Things (IoT) in which distributed things or components exchange and process information. The combination of cloud server-based big data processing technology and the IoT begets the Internet of Everything technology. In order to secure the sensing technology, wired/wireless communication and network infrastructure, service interface technology, and security technology required for implementing the IoT, recent research has been focused on sensor network, Machine to Machine (M2M), and Machine Type Communication technologies. In the IoT environment, it is possible to provide an intelligent Internet Technology (IT) that is capable of collecting and analyzing data generated from connected things to create new values for human life. The IoT can be applied to various fields such as smart home, smart building, smart city, smart car or connected car, smart grid, health care, smart appliance, and smart medical service through legacy Information Technology (IT) technology and convergence of various industries.
Thus there are various attempts to apply the IoT to the 5G communication system. For example, the sensor network, Machine to Machine (M2M), and Machine Type Communication (MTC) technologies are implemented by means of the 5G communication technologies such as beamforming, MIMO, and array antenna. The application of the aforementioned cloud RAN as a big data processing technology is an example of convergence between the 5G and IoT technologies.
As described above, studies are being conducted to develop communication technologies in various fields to meet the increasing wireless data traffic demand. Examples of those technologies include Device to Device (D2D) communication system, carrier aggregation system for operating multiple cells, and massive antenna system for use of a plurality of antennas.